Monolayer chemical beam etching

• Published in: Journal of crystal growth Vol. 135; no. 3; pp. 377 - 382
• Main Authors: Tsang, W.T., Chiu, T.H., Kapre, R.M.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.02.1994; Elsevier
• Subjects: Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Molecular, atomic, ion, and chemical beam epitaxy; Physics; Surface treatments; Real time systems; Gallium arsenides; Atomic layer method; Inorganic compounds; Semiconductor materials; Epitaxy; CBE; Binary compounds; Surface treatments; Etching; RHEED; Experimental study; Chemical beam condensation; Kinetics; Monitoring
• ISSN: 0022-0248; 1873-5002
• DOI: 10.1016/0022-0248(94)90126-0

We have developed an etching process with real-time counting of each monolayer removed, thus achieving etching with monolayer precision and control. This is an exact reversal of molecular beam epitaxy or more specifically in this case, chemical beam epitaxy (CBE). This new etching capability which we refer to as monolayer chemical beam etching (ML-CBET) is achieved by employing in-situ reflection high energy electron diffraction (RHEED) intensity oscillation monitoring during etching. Etching is accomplished in high vacuum by injecting AsCl 3 directly into a CBE growth chamber impinging on a heated GaAs substrate surface. Having both epitaxial growth and etching integrated in the same process and both capable of ultimate control down to the atomic layer precision represents a very powerful combination. This permits instant switching from growth to etching and vice versa, clean regrown interfaces critical for device applications, direct modification of surface chemistries during etching or growth, and high temperature etching (500–570°C for InP and 500–650°C for GaAs) unachievable in conventional etching processes. The temperature and flux dependence of etching rates are also studied using RHEED oscillations. Results indicate that ML-CBET is predominantly via a layer-by-layer mechanism under the present etching conditions studied.